Seal Island Bridge Deck Replacement

The Seal Island Bridge is located on a vital stretch of the Trans-Canada Highway. Because closing the bridge to facilitate a recent rehabilitation and deck replacement project would have a significant impact on the region's economy, minimizing traffic disruption was a major factor in choosing a structural repair system. This article discusses the evaluation and construction process for the bridge project. After considering several alternatives, a precast concrete bridge deck was chosen because it met the most important criteria: durability; constructibility and ability to meet stringent construction schedules while minimizing traffic disruption; cost-efficiency in terms of both capital and life cycle costs; and contribution to the stiffness and damping of the supporting structure for vibration control. The existing steel superstructure was reinforced to carry the weight of the new structure and to meet the current design live load code. The construction sequence allowed the retention of a driving lane while replacing half of the deck. Only three overnight closures per week were required. The new deck system is lighter than a conventional cast-in-place concrete deck system, which reduced the amount of truss reinforcement required. The new deck system is also more durable than conventional systems since it is designed to be crack-free under service load conditions.